One of the most beautiful things about the concept of worship in Islam is the truly unique way in which it incorporates fear and hope within the hearts of the worshippers of Allah. Understanding how to combine these two qualities into the worship (ibadah) of Allah is one of the most essential things that every Muslim must grasp, not least because every sect which has drifted from the Straight Path has strayed in the aspect of worship. The deviation of the other religions in this regard is clear for all to see: “God is love! Jesus is love!” say the Christians, denying the fact that Allah should be feared too. As for the Jews, their hearts were filled only with hope; hope that the Fire will never touch them, since they were the “Promised People”.
In Islam however, no worship is complete without the presence of both qualities: hope in His Mercy and fear of His Punishment.

Surah Fatiha is a surah which we all know and we read it in every Rakaat of every Salaah. Allah draws our attention towards these two qualities here as well.

ٱلرَّحْمَـٰنِ ٱلرَّحِيمِ
Most Gracious Most Merciful.
When we mention these two names of Allah, then we have HOPE. Since He is the One who is full of Mercy, and we hope He will forgive our mistakes and shortcomings.

The need to have FEAR in our worship is shown by the next ayah of Surah al-Fatihah.
مَـٰلِكِ يَوْمِ ٱلدِّينِ
When we recite this ayah, we remind ourselves of the Day of Judgement – that awful Day, when all of humanity shall stand before Allah. People will appear drunk though they are not. On that Day, every person will stand before Allah and account for his deeds, knowing that not even the smallest action which he did is hidden from Allah:

So both fear and hope should be present in our hearts in equal proportions. Anas RA reported that the Prophet ﷺ entered upon a young boy who was dying. The Prophet ﷺ asked, “How are you?” The boy replied, “O Messenger of Allah, I am in between hoping in Allah and fearing for my sins.” The Prophet ﷺ said, “The like of these two qualities do not unite in the heart of a servant except that Allah gives him what he hopes for and protects him from what he feared.” [Sunan at-Tirmidhi and Sunan ibn Majah]

Therefore whenever we do a good action, we should hope that it has been accepted by Allah, but at the same time we should also have fear that maybe it isn’t enough or that the good deed has not been worthy of acceptance. Likewise when we sin, we should have hope that Allah will accept our repentance and forgive us, but we should also fear that we may be accountable for it.

This balance should be reflected in our da’wah. So when we invite others to the Truth, we should not give them the impression that ‘they have nothing to worry about’, nor do we suggest that ‘they are doomed forever’. Rather we couple warnings with encouragement. We inform them of the horrors of the Fire and tell them about the bliss of Paradise. Just as we find Allah telling us in the Qur’an:

إِنَّ رَبَّكَ لَسَرِيعُ ٱلْعِقَابِ ۖ وَإِنَّهُۥ لَغَفُورٌ رَّحِيمٌ
“Verily your Lord is quick in punishment and verily He is the Oft-Forgiving, the Giver of Mercy.” [Al A`raf 7:167]

And the scholars of Islam say, “He who worships Allah with hope only is a murji’i. He who worships Him in fear only is a haruri [khariji]. But he who worships Allah in fear and hope is a muwahhid mu’min [a believer upon tawhid].”

The murji’a were a sect that emerged within the first century of Islam. The people of this sect believe that sins do not affect faith i.e. no matter what sins a person commits, his Imaan (faith) is complete and perfect. They worship Allah only with hope because they believe that as long as one believed and testified to Islam, they would enter Paradise regardless of their actions.

Unfortunately, all too often nowadays we find a similar attitude amongst many Muslims today, which is why we find that so often we try to advise someone to turn to the Deen and abandon sin, they just point to their hearts and say, “Allah knows what is in my heart”, or “Allah forgives”, or something else like that.

As for the khawarij, they worshipped Allah in fear only because they held that anyone who commits major sins was a disbeliever and would therefore dwell in Hellfire forever. This of course is gross extremism and straying from the correct path.
Therefore we should never say of anyone that he or she is a ‘lost cause’ or ‘doomed’ or the like of this, for it is a great sin. However, we fear for those who commit major sins because they have been threatened with punishment in the Qur’an and the Hadith. However it is up to Allah whether He chooses to punish them or whether He will forgive them.